Figure 1

Cultured rat microglia display chemokinesis, chemotaxis, and invasion. (A) To monitor chemokinesis (random migration) in two dimensions, cultured rat microglia were imaged for 45 minutes under phase-contrast microscopy at 37°C and 5% CO₂. A representative video frame capture, in which the numbered cells were tracked and analyzed (results in (c)). Inset: higher-magnification images show a lamella and extension of the leading edge in a migrating cell, but not in an immobile bipolar microglial cell. Scale bar: 80 μm (upper image), 40 μm (lower image). (B) Higher-magnification phase-contrast image showing a large ring-like structure in the lamella (circled), and a uropod at the trailing edge (arrow). Scale bar: 20 μm. (C) Each of the 28 microglial cells marked in (a) had a lamella at some time during the monitoring period. During a 10-minute examination period, these cells were classified as migrating in the direction of the lamella, in the opposite direction, or not moving. (D) Quantification of microglia transmigration through pores of 8 μm diameter in filters in the upper well of Transwell™ chambers. Microglia displayed chemotaxis toward 300 μM ATP added to the lower well. Values on bars are mean ± standard error of the mean (SEM) (n = 5). (E) Microglia invaded through Matrigel™-coated pores in the BioCoat Matrigel™ Invasion chambers, and invasion was increased by adding 300 μM ATP to the lower well. Values on bars are mean ± SEM (n = 6).